Abstract: This study are focused on four problems:(1)Headspace gas chro- matographic method of analysis ethanol in forensic blood and urine sp- ecimens;(2)Time-course changes of BAC and UAC of human bodies after ethanol ingestion;(3)Postmortem production of ethanol in human subjects who had not drunk before death,ahd(4)postmortem changes of ethanol concentrations in blood and urine specimens,.In this paper,head space gas chromatographic method for analysis of ethanol in blood and urine is developed,Some factors affecting sensitivity,precision and accuracy of the headspace gas chromatographic analysis are discussed, including“saltingout”effect,bath temperature,equilibration time, relative volumes of sample in the vial etc.By optimizing conditions for analysis of headspace sample,the method has become rapid,sensi- tive and reproducible.